C3H murine lymphoid cells will be treated with fractions of xenogeneic immunogenic ribonucleic acid (IRNA) extracted from the spleens and lymph nodes of rabbits and guinea pigs immunized with the 4198 polyoma-induced fibrosarcoma tumor, tumor membrane, soluble tumor-associated antigen, or control material (L cells, SV40-transformed cells, normal C3H tissue, extracts of above). Animal treatments will consist of the injection of the syngeneic lymphoid cells pre-treated with the various RNA's and fractions thereof into C3H mice, according to two protocols. The first protocol describes treatment of the mice with RNA-treated lymphoid cells, followed by tumor challenge, to evaluate immunoprophylactic effects of IRNA. The second involves treatment of animals after excision of a growing tumor, with the placement of "metastic" tumor concurrent with IRNA-teated lymphoid cell injection, to assess the immunotherapeutic value of IRNA in vivo. At all stages of the project, serological testing will be performed to detect the presence of cytotoxic, "blocking" or "unblocking" factors in the sera of tumor-bearing, control, and RNA-treated animals, using in vitro cytotoxicity testing and complement fixation. In addition, the immunocompetence of IRNA-treated lymphoid cells will be evaluated in vitro by cytotoxicity testing on cell monolayers, and by blastogenic transformation and production of migration inhibitory factor (MIF) in the presence of the various antigen preparations. Attempts to enhance the specificity of the IRNA will be made using isolated tumor antigens as immunogens in the xenogeneic IRNA donors.